CHARCOAL, VS. COKE AND "ANTHRACITE IRON. l6l
The greater the temperature in a blast furnace, the more silicon can iron absorb. The lower heat derived from charcoal furnaces causes less silicon to be taken tip than by iron in coke or anthracite furnaces. From this circumstance, combined with the fact that charcoal fuel is free from sulphur, we find that charcoal iron generally contains very little sulphur, with low silicon. The more general uniform workings of charcoal over coke furnaces and absence of sulphur in charcoal iron, leaves much less chance for the other elements — silicon, manganese, phosphorus, etc., to cause radical variation in the size of the grains; and hence we find, as a general rule, that charcoal iron is more uniform in grain than coke or anthracite irons.
The greater strength and homogeneity of charcoal over the present coke or anthracite iron, also in its possessing very low sulphur, as a rule, will, in the author's estimation, forbid its expulsion from the market. There are certain kinds of work for which charcoal will generally prove superior over other irons. These can be classed in the following -order: (i) Chilled work, (2) gun manufacture, (3) hydraulic and steam cylinder castings. Heavy gearings and large castings require high strength, combined with softness sufficient to permit finishing. Coke iron is now used in nearly all the specialties, but where it is intended to replace charcoal special care is often necessary to watch the sulphur contents in order to get them as low as possible. Where the coke or coal fuel and ore are very low in sulphur, coke or anthracite iron can be made which may often answer many purposes of charcoal pig. Charcoal pig iron, on the whole, is poorer in silicon and phosphorus, as well as sulphur, than a coke or anthracite pig metal.iven is simply an average of the whole, generally taken from the two ends andith the uncertainty of furnace workings when in urgent need of ten hundred jon of iron; and Sir........................ 2,720 "